1. Field
Embodiments of the present invention relate to a nut screw conveying device which allows flexible change of output stroke using a variable pitch nut.
2. Description of the Related Art
Generally, a nut screw conveying device uses a nut and a screw to convert rotational power into translational movement. The nut screw conveying device transmits power by rotating the nut or the screw and rectilinearly moving along mutually engaged threads.
Spiral inner circumferential grooves are formed on the inner circumferential surface of the nut, and spiral outer circumferential grooves are formed on the exterior of the screw to face the nut. Balls or bearings are provided between the screw and the nut in order to roll along the inner circumferential groove of the screw and the outer circumferential groove of the screw when the screw is rotated by the rotational power transmitted thereto to cause the nut to translate.
The nut of such a nut screw conveying device is configured to have a single pitch. Accordingly, when rotational power is converted into translational movement, the relation of an output stroke of the nut to a rate of rotation input to the screw is kept constant over the entire movement section.
Since the conventional nut screw conveying device as above operates with the relation of the output stroke of the nut to the rate of rotation input to the screw kept constant over the entire movement section, it may not be applicable to an apparatus in which the output stroke of the nut corresponding to a rate of rotation input to the screw varies over a certain section.